Opioid peptides, receptors, and immune function

NIDA Res Monogr. 1990:96:220-33.


The studies have clearly demonstrated that binding sites for opioid peptides, beta-endorphin, and methionine-enkephalin exist on T lymphocytes. beta-Endorphin appears to be immunodepressant, whereas methionine-enkephalin is immunostimulant. Both in vitro and in vivo studies have shown that methionine-enkephalin can influence some immune functions. Since in vitro modification of immune function requires very low concentrations, it is reasonable to believe that methionine-enkephalin plays a physiological role in the immune system. Although not well established, methionine-enkephalin appears to activate T lymphocytes via opioid receptors and triggers a series of intracellular signals leading to the activation of receptors for interleukin-2 (IL-2), OKT10, and active sheep T red blood cell receptors. Methionine-enkephalin enhances the activity of NK cells and induces the production of IL-2, which in turn may recruit and activate other T-cell subsets like CD3 and CD4. Methionine-enkephalin also enhances mitogen-induced proliferation of lymphocytes. Since preliminary studies with methionine-enkephalin in ARC patients have provided beneficial effects by the improvements in their symptoms, it will be worthwhile to extend these observations to a larger number of patients with ARC and AIDS. Finally, it appears that some endogenous opioid peptides and their analogs, in addition to methionine-enkephalin, may provide therapeutic benefits not only in ARC and AIDS but also in other immunodeficient states.

Publication types

  • Review

MeSH terms

  • Acquired Immunodeficiency Syndrome / blood
  • Acquired Immunodeficiency Syndrome / immunology*
  • Animals
  • Antibody Formation
  • Binding Sites
  • Enkephalin, Methionine / immunology*
  • Enkephalin, Methionine / metabolism
  • Heroin Dependence / immunology*
  • Heroin Dependence / metabolism
  • Humans
  • Morphine Dependence / immunology*
  • Morphine Dependence / metabolism
  • Narcotics / immunology*
  • Narcotics / metabolism
  • Receptors, Opioid / immunology*
  • Receptors, Opioid / metabolism


  • Narcotics
  • Receptors, Opioid
  • Enkephalin, Methionine